Significance of serum myoglobin in neuromuscular diseases and in carrier detection of Duchenne muscular dystrophy

Abstract

In a retrospective study, the serum myoglobin concentration (S-myoglobin) was determined in patients with neuromuscular diseases and in carriers of Duchenne muscular dystrophy (DMD). Myoglobin was quantified by a sensitive radioimmunoassay. Serum creatine kinase (CK, EC 2.7.3.2) activity (S-CK) and serum creatine kinase B-subunit activity (S-CKB) were determined for comparison. Sera from 70 patients with various neuromuscular diseases and from 17 female relatives of patients with DMD were analysed. Increased levels of S-myoglobin were found both in dystrophic and in spinal myopathies. Because of a marked overlap of the range of values between the different dystrophic myopathies and even between the dystrophic and the spinal myopathies, S-myoglobin is of little value in the final diagnosis of neuromuscular diseases. In the detection of carriers of DMD, simultaneous determination of S-myoglobin and S-CK gave a higher detection rate compared to the detection rate with S-CK. S-CKB was normal in all carriers and only elevated in some of the patients with DMD and limb girdle muscular dystrophy.